Absorbent articles such as diapers, training pants, incontinence products, feminine hygiene products, swim undergarments, and the like conventionally include a liquid permeable body-side liner, a liquid impermeable outer cover, and an absorbent core. The absorbent core is typically located in between the outer cover and the liner for taking in and retaining liquids (e.g., urine) exuded by the wearer.
The absorbent core can be made of, for instance, super absorbent particles. Many absorbent particles, especially those sold under the trade name HUGGIES™ by the Kimberly-Clark Corporation, are so efficient at absorbing liquids that it is sometimes difficult to tell whether or not the absorbent article has been insulted with a body fluid.
Accordingly, various types of moisture or wetness indicators have been suggested for use in absorbent articles. The wetness indicators may include alarm devices that are designed to assist parents or attendants to identify a wet diaper condition early on. The devices produce either a visual or an audible signal.
In some aspects, for instance, conductive threads or foils have been placed in the absorbent articles in the machine direction. The conductive materials serve as conductive leads for a signaling device and form an open circuit in the article that can be closed when a body fluid, such as urine, closes the circuit. In other aspects, disposable absorbent articles such as roll products, wipes products, health care products, incontinence products, feminine care products, diapers and training pants may also include conductive threads or foils.
Incorporating a wetness sensing system into an absorbent article during its manufacture, however, can be problematic with respect to quality control. Standard absorbent articles are typically inspected using a metal detector to detect whether metallic foreign materials of any kind have been introduced into an absorbent article. Metal detectors are also currently used by many manufacturers to confirm that no foreign metal objects have accidentally been placed into any product packages. Absorbent articles or packages including such a foreign materials are culled from the process and disposed of. Absorbent articles incorporating a wetness sensing system including conductive foils or other similar structures, however, may not always be accurately inspected for foreign materials using a metal detector because such absorbent articles already include a certain amount of metal. Thus, a need currently exists for a quality control process that can be used to verify that the absorbent articles incorporating a wetness sensing system do not include foreign materials.